| 摘要 |
PURPOSE:To simplify the constitution of the doughnut directional microphone by fitting a differential-type microphone at the center of an acoustic tube so that a front part of a vibration film can point outside. CONSTITUTION:A differential-type microphone 4 is fitted at the center of an acoustic tube 5 so that a front part of a vibrating film can point outside. An acoustic path to a rear part of the vibrating film is constituted of the acoustic tube 5. The sound pressure applied to the front part of the differential-type microphone 4 becomes nondirectional, while the sound pressure applied to the rear part through the acoustic tube 5 becomes bidirectional in Y-Y'' axis direction. An output of the differential-type microphone 4 turns out to be a difference output between the sound pressure applied to the front part of the microphone 4 and that applied to the rear part of the microphone 4, and a doughnut-type directional pattern can be obtained as the result. |
